ℌ2 pseudo-optimality in model order reduction by Krylov subspace methods

New sufficient conditions for ℌ₂ pseudo-optimality in Krylov-based model reduction of linear dynamical systems are presented. The conditions are easy to evaluate and permit first applications: a new algorithm to generate ℌ₂ pseudo-optimal reduced models with respect to the projecting subspace and a procedure to generate superior local optima in iterative methods. Numerical examples illustrate the contributions.